A New Type of Hot Air Engine

[VincentG]

All sorts of good things to try. Luckily, the surface of a 3d printed part will be inherently rough, and may have the shark skin effect you are looking for. I think with your 3-d profile, many smaller tubes will be beneficial in place of one larger one, as there must be a sweet spot between flow rate and the area of the conduit in relation to the viscosity of the gas flowing through. So it may be a very different design from the intake valve compared to the exhaust valve.

[theuns]

This links to the PDF manual for the air pump.
https://www.econologie.com/forums/downl ... 6f20195c21
It will start to download automatically. The double piston is 42mm at the large side and about 10mm at the small side.

Related to the post:

I have a YONGHENG high (4500 psi) pressure air pump that has a similar second stage compressor piston but I'm not sure of the internal workings. I think some port system connects the two cylinders, however the two pistons are joined as one unit. I haven't had it apart, but this image from an ad on eBay shows the duel low and high pressure piston

Resize_20230317_173100_0051.jpg

It generates an enormous amount of heat and requires using a water pump to circulate cold water (many people recommend using ice water) around the high pressure cylinder to prevent heat damage.